Voltage smoothing and regulating system



Nov. 1,1932. Q H, GREEN VOLTAGE sMooTHING AND REGULATING SYSTEM Original Filed Nov. 24. 1926 Illllllllilllllrlln Patented Nov.` Yl, 1932 UNITED STATES PATENT oFFlcE CECIL H. GREEN, F BEOOKLINE, MASSACHUSETTS, ASSIGNOB. T0 RAYTHEON INC., 0F

CAIBBIDGE, MASSACHUSETTS,

A CORPORATION 0F MASSACHUSETTS VOLTAGE SHOOTHING AND BEG'ULATING SYSTEM Application led November 24, 1926, Serial No. 150.500. Renewed December 17, 1930.

This invention relates generally to means for obtainin a constant potential from an electric circult subject to voltage and/or current changes, more articularly to a oaseous conduction device tliat functions to Iliy-pass excess current. My device has special adaptation to the furnishing of potential having invariable magnitude to the plate circuit of a vacuum tube amplilier demanding the superlative degree of potential constancy and fiatness of regulation. While the arrangement hereinafter described exhibits remarkable cooperation with a rectifier and filter to form a eliminator so-called, it is to be distinctly understood that utility is not limited to radio but has broad application to circuits in general that require a steady source of potential under conditions of varying load or in case the primary source of energization is sub ject to potential variations. In a sense, my device may be considered as having a combined voltage smoothing and regulating characteristic and may be used in addition to or in lieu of a lter; when utilized in a filter combination, it will be apparent that its presence procures a substantial reduction in size of the existing elements.

. It has been proposed in the art to connect either vaporous or gaseous discharge devices across the line for the purposes above mentioned but in each instance, severe limitations attend their use due chiefly to the internal characteristics of the device employed. In the case or" vapor discharge, i. e. mercury cathode, an auxiliary circuit is necessary to vaporize the liquid, and unless the starting means is therafter rendered ineffective, the low potential drop of the discharge precludes its use singly as a shunt across a line carrying in excess of twenty or thirty volts.

I am aware that there have been employed gaseous discharge devices in which an ionized region between electrodes of diiferent areas presents asymmetrical conductivity to volte age variations. However, the construction of these devices has been such that the ionized region spreads to adjacent surfaces, as, for example, the leading-in conductors, the glass envelope and reentrant stem causing vacillation of the arc and deleterious effects in general at the places mentioned. In order to improve the operation it has been customary to reduce the potential applied in a single device to a magnitude, the order of which incidentally is insufficient to furnish plate current. As is apparent, the presence of the unrestricted discharge imparts to the tube an erratic characteristic even under reduced electromotive force which fact preludes ei'l'ective elimination of line disturbances. Furthermore, inasmuch as the devices of prior art utilize the same potential for the functions of starting and operating, whereas lgood practice demands a substantial difference in favor of a compromise of voltage must be made which obviously results in decreased eficiency of the device as a Whole. The compromise is particularly harmful in the case of unrestricted discharge since in this form of conductor the difference in the starting and operating voltage is considerable.

N ow, I propose to utilize as a shunt or current by-pass certain tube structure that operates by reason of gas ionization and in Which the former,

the ionized region is confined to a definite space. I also propose to separate completely the processes of starting and operating, adjusting each to the individual requirements for best performance of the shunt as a Whole which usually dictates an initial voltage that 1s automatically discontinued in favor of a lower operating voltage having an order of magnitude not less than that demanded for plate energization. For the purposes above stated I provide an enclosed cathodal chamber with two anodes projecting therein, the function of one of the latter being limited strictly to starting and the other to operating thereafter.

The primary object of this invention is to provide a simple, compact and efficient device or obtaining constant potential from a circuit or source Whose voltage is subject to fluctuation or the current flow of which materially varies. Another object is to provide a gaseous discharge tube of such characteristics as to maintain a substantially constant voltage at its terminals irrespective of substantial variations of current flowing therethrough. A further object is to devise ,i structure having separate and clearly defined potentials for the starting and operating conditions. A still further object is to provide a combined filter and current by-pass, the latter deriving its starting) potential from points within the system. ther obJects and features will be apparent upon perusal of the following description when considered in view of the accompanying drawing in which Fig. 1 illustrates a preferred embodiment of my invention while Fig. 2 shows an alternative arrangement.

Referring to Fig. 1, numeral 1 represents a transformer, the primary of which is energized by a source of potential ordinarily that of the house supply. Across the secondary I connect the usual surge condensers and a rectier, preferably of the double wave Raytheon type B. H. so-called as disclosed and claimed in the applications of Charles G. Smith, Serial No. 526,095 now Patent No. 1,617,179, granted February 8, 1927,'and entitled Electrical apparatus7 and Vannevar Bush, Serial No. 22,988 entitled Gascous conduction. However, all forms of single and double Wave rectifiers are adapted to my system. The current from the rectifier passes through low-pass filter F consisting of series chokes 3 and shunt condensers 4 to terminals 5.

Across the line and intermediate the filter and said terminals, I arrange a gaseous discharge device of the Raytheon type supra, the construction of which is such as to have the desirable characteristics mentioned hereinbefore. The device consists essentially of a tube 6 which may be formed of glass, a hollow cathode 7, anodes 8 which project slightly into the cathode, cylindrical insular, tion members 9, preferably of lavite, and a base comprising metallic cylinder 10 secured by a suitable compound to the tube in the usual manner. The bottom of the cylinder is closed by porcelain disk 11 into which the connectorplugs project. The tube 6 has reentrant stem 12 provided with two tubular projections 13 which extend into recesses in the bottom of members 9, the latter being slipped over the projections 13 and held in position by cathode 7. The anodes 8 are mounted in openings in members 9 concentrically with projections 13 and openings 14 in the cathode. The cathode is preferably formed in two parts, the upper part comprising a conically shaped electrode and the lower part 15 comprising a cover fitting the open end of the cone. As stated in the applications supra, members 9 are spaced from the anodes a distance materially less than the free mean path of the electrons present and serve to prevent the passage of latter between either anode and the outer surface of the cathode. The ionic activity is thus confined to the space enclosed by the cone, i. e. the region adjacent to the zation within the cone has the decided beneficial effect of reducing the potential drop at the surface of electrode, thus decreasing in like degre'e the internal losses of the device. Moreover, the symmetrical shape of cathode oders an advantage by Way of smooth operation. If, desired, I may further reduce the voltage drop at the cathode by coatlng its inner surface with a metal of the alkali group, as sodium, potassium, caesium or one belonging to that of the alkali earth, as barium, strontium or the like. The cylindrical members 9 contain circular recesses 16 adjacent to the openings 14 to prevent or reduce to a. negligible factor the tendency of current to How between cathode and either anode along the surface of insulation. The openings 14 are of such size as to provide space between the cathode and operating anode, preferably of the order of the mean free path of electrons within the region of the cathode although a spacing of slightly less dimension will give satisfactory results. The peripheries of the openings are preferably bent downwardly to fit into the recesses 16 as shown. While the cathode may be supported solely by cylindrical members 9, I preferto partly depend for support on the centrally located cathode lead 17 which is joined electrically to one of the connector plugs. After evacuating the tube and removin the occluded material, monatomic gas o the helium group or a mixture of same is admitted\at a pressure approximating 15 mm. Hg. Now as stated hereinbefore, I propose to limit the function of one anode to that of starting and for this purpose connect the latter through resistance 18 to a position either prior to or in the filter F from whence high potential may be derived. This potential should be of an order sufficient to initiate a small reverse current between cathode and starting anode producing gas ionization withing the cone to effectuate reduction of internal resistance With consequent passage of current between the cathode and operating anode. The unilaterally insulating feature attributed at present to the difference in effective area of electrodes prevents substantial passage of current in the reverse direction. The resistance 18, of a size depending upon the impedance odered by the filter to pulsatory current passes to the starting anode, the total potential available at the outputterminals of rectifier 2, but after current flows, its inherent voltage drop causes a decrease in potent-ial at the anode precluding further current fiow and automatically cutting out the starting expedient. The device thus ionizes at the potential available across the rectifier after which control is automatically shifted to the lower voltage impressed across the outgoing line. The cathode and second anode are connected across the main lines through C5 inner surface of the latter. The intense iOncurrent limiting resistance 19 at a point sub- 13 sequent to the filter and effectively shunt fluctuations of current together with a small portion of the steady component to preserve the current path between anode and cathode. However, the starting anode is always in a position to start anew an ionized condition and in all probability does thus'function intermittently. The resistance 19 also rovides a potential drop necessary to adapt t e rectifier voltage to the requirements of amplifier plate energization.

have discovered that the structure of the described tube lends itself admirably to fiat regulation by operating under conditions of progressive ionization to pass current of varying amplitude without corresponding or proportional change in voltage across its terminals; thus for varying loads between O and 100 milliamperes, there is obtainable voltage regulationwithin a fractional part of one percent.

While I have shown the starting and operative anodes as connected to the same side of the line causing initial ionization between one anode and the cathode, I may temporarily cause conduction between the starting and operating anodes. Thus in Fig. 2 between one of the anodes 8 and a point on the cathode side of the line, I interpose resistance 18 in the same manner and having like function as the correspondingr element in Fig. 1. However, current limiting resistance 19 is also removed to the cathode side, the operating anode remaining on the same line as in the preceding figure. Under these conditions tlie ionization necessary for starting takes place between the two anodes after which. the cathode displaces the starting anode to pass a small amount of steady current and in addition the total variable component as was explained with reference to the preceding gure. In view of the foregoing, it will be noted that there has been provided a simple and effective means for obtaining a substantially constant voltage from a circuit whose potential or current may be subject to material variations.

I claim:

1. In combination, a source of current providing a varying and a steady component and means for effectively removing said varying component, said means including a low-pass filter and a gaseous discharge device having two anodes and a cathode, said anodes beingconnectedr onv opposite sides of said filter.

2. A wave suppressing network supplied with waves of varying potential and comprising a member in series with said waves, and a gaseous conduction device :in shunt thereto and comprising a hollow cathode and separate anodes, the parts being arranged for gaseous discharge between the anodes and the interior of said cathode, said anodel being connected at different points along said network whereby there is a difference of potential between them.

3. In combination, a source of direct eurrent,`means for reducing variations in the potential derived from the source, said means coriprising impedance in series therewith an means .or initiating discharge including an impedance connected to said source.

4. In combination, a source of current providing a varying and a steady component and means for effectively removing said varying component, said means including a device in shunt to said source and having a plurality of anodes with means whereby one of said anodes ceases to function upon operation of another of said anodes.

5. A source of direct current, a gaseous conduction tube in shunt thereto to absorb variations in the potential derived from said source, said tube including starting and operating anodes and impedances of different value connected between each of the anodes and said source. v

6. A source of direct current comprising a filter section, means for providing a pulsating direct current to said section, a glow discharge device having two electrodes 0f one polarity and one electrode of an opposite polarity, a resistance, means for connecting said two similar electrodes at diii'erent points of the filter section, one of said electrodes bek ing connected thereto through said resistance and means for connecting said other electrode to the other side of said filter section.

7. A source of a filter section, means sating direct current thereto, a glow discharge device having two anodes and one cathode, a pair of resistances, said anodes being connected to two different points of said iiltersection through said resistances and said cathode being connected to the other side of said filter section.

8. A source of direct current providing a varying and a steady component of potential, a circuit in shunt thereto including a gas discharge tube, said tube containing electro'des spaced apart a distance of the order of the mean free path ofthe electrons in the gas.

9. In combination, rent, a load fed by said current, a glow discharge device connected across said load, said glow discharge device having a hollow cathode and two anodes presented to the interior thereof, and means for applying a higher potential to one of said anodes than to the other.

10. In combination, a source of direct current, a load fed from said source, a glow discharge device connected across said direct current comprising for supplying a pulsaid glow discharge device having a hollow cathode and two anodes presented to the ina source of'direct curload,

a gaseous discharge in shunt thereto and f charge a terior thereof, means for impressing a higher potential upon one of said anodes than upon the other, and means for limiting the discharge passing through the anode upon which said higher potential is impressed.

11. A source of direct current providing a varying and steady current co-mponent of potential, a circuit in shunt thereto including a gas discharge tube, said tube having a hollow cathode of extended area, an anode presented to the interior thereof, and means for restricting the discharge to a restricted portion at the end of the anode.

12. In a filter for removing pulsations from a pulsatory direct current received from a source and supplying smoothed current to a load comprising, a network having a pair of input terminals for receiving the pulsatory direct current, a pair of output terminals for delivering smoother direct current, impedance and conducting elements constituting circuit connections of opposite polarity serially connected between said input and output terminals for passing the liltered current from said input 'terminals to lsaid output terminals, said network including a gaseous discharge tube having a pair of electrodes connected in shunt to points on said circuit connections of opposite polarity, and designed and spaced to discharge a diverted portion of the input current at a predetermined voltage and reduce the pulsations of the current delivered at said output terminals, said pair of electrodes having a starting voltage insufficient to start the discharge at the normal voltage, and an additional electrode in said tube connected to a point of said network applying thereto a voltage higher than that between said electrodes suiicient .to break down the gas and start said diverted discharge between said pair of electrodes.

13. In combination, a source of direct current having a steady component and variable components superimposed thereon, a load, a

filter network including impedance and conducting elements constituting a pair of circuit connections of opposite polarity serially connecting said source to said load, to suppress the variable current components and pass the steady current smoothed to said load, and a gaseous discharge tube having a pair of electrodes connected in shunt to points on said circuit connections of opposite polarity designed and spaced to disdiverted portion of current from said source at a predetermined voltage and reduce the variable component of the current delivered to said load, said pair of electrodes having a starting voltage insucient to start the discharge at the normal voltage, and an additional electrode in said tube connected Ain series with an impedance to a point of said network applying thereto a voltage higher than that between said electrodes sufpass the steady current smoothed to said load, v and a gaseous glow discharge tube having icient to break down the gas and start said diverted discharge between said pair of electrodes.

14. In combination, a source of direct Vcurrent having a steady component and variable components superimposed thereon, a load, a filter network including impedance and conducting elements constituting a pair of circuit connections of opposite polarity serially connecting said source to said load, to suppress the variable current components and pass the steady current smoothed to said load, and a gaseous glow discharge tube having a large surface cathode and a small surface anode connected in shunt to negative and positive points on said circuit connections of opposite polarity designed and spaced to discharge a diverted portion of current from said source at a predetermined voltage and reduce the variable component of the current deliveredv to said load, said cathode and a main anode having a starting voltage insuicient to start the discharge at the normal voltage, and an additional small surface anode in said tubeconnected to a point of positive potential of said networkapplying thereto a voltage higher than that of said main anode sullicient to break down the gas between said cathode and main anode and start tween.

l5. In combination, a source of direct current having a steady component and variable components superimposed thereon, a load, a filter network including impedance and conducting elements constltuting a pair of circuit connections of opposite polarity serially connecting said source to said load, to suppress the variable-current components and a large hollow surface cathode and a small surface anode presented to the interior thereof connected in shuntto negative and positive points on said circuit connections of opposite polarity designed and spaced to discharge a diverted portion of current from said source at a predetermined voltage and reduce the variable component of the current delivered to said load, said cathode and a main anode having a starting voltage insufficient to start the discharge at the normal voltage, and an additional small surface. anode in said tube connected to a point of` positive potential of said network applying thereto a voltage higher than that of said main anode suliicient to break down the gasV between said cathode and main anode and start said diverted discharge therebetweeiir said diverted discharge therebe- C 16. In combination, a source of digect cur-# rent having a vsteady component andvariable components superimposed thereon, a load@ a ilter network including impedance and ally connecting said source to said load, to suppress the variable current components and pass the steady current smoothed to said load, and a gaseous glow discharge tube having a large hollow surface cathode and a small surface anode presented to the interior thereof connected in shunt to negative and positive points on said circuit connections of opposite polarity designed and spaced to discharge a diverted portion of current from said source at a predetermined voltage and reduce the variable component of the current delivered to said load, said cathode and a main anode having a startingr voltage insuficient to start the discharge at the normal voltage, and an additional sniall surface anode in said tube connected in series with an impedance to a point of positive potential of said network applying thereto a voltage higher than that of said main anode sulicient to break down the gas between said cathode and main anode and start said diverted discharge therebetween.

Signed by ine at Cambridge, Massachusetts, this 18th day of N oveinber, 1926.

CECIL H. GREEN. 

